Column packing and method for manufacturing the same

ABSTRACT

First line element made of, e.g., wire and second line elements made of, e.g., wire are disposed so that they cross each other and they are welded together at crossing points to form a net. The net is pressed to form an undulating net. An undulating net of a first layer and an undulating net of a second layer are laid one upon the other in such a manner that crossing points of the undulating net of the first layer alternately come into contact with and are separated from crossing points of the undulating net of the second layer. The crossing points which are in contact with each other are welded together by a welding machine. Subsequently, undulating nets of a third to n-th layers are similarly processed to form a three-dimensional net-like structure.

BACKGROUND OF THE INVENTION

[0001] This invention relates to a column packing filled in a devicewhich is divided in a plurality of chambers or channels connected to oneanother and performs material transfer, heat exchange or mixing betweengases, liquids or gas and liquid. The invention relates also to a methodfor manufacturing such column packing.

[0002] Japanese Patent Application Laid-open Publication No. Hei3-203976 discloses a column packing of this type. This column packing ismade up of a plurality of permeable sheets which are disposed inparallel to one another and extend in the direction of a main stream offluid. Projecting portions of these permeable sheets are disposed in thedirection that crosses the main stream of fluid and these projectionsfunction as spacers between the adjacent permeable sheets. This packing(hereinafter referred to as “X-packing” because the cross section of ajoint portion between two adjacnetn permeable sheets assumes the shapeof the letter X) is beneficial in that fluid flowing down along thepermeable sheets is repeatedly joined, mixed, horizontally dispersed andredistributed at each joint of the permeable sheets. Thus, fluid flowwhich was not uniform when it was charged in the device graduallybecomes uniform resulting in an optimum material transfer or heatexchange. Moreover, gas charged in the device passes through the liquidflowing along the inclined surfaces of the permeable sheets andnecessary contact between the gas and the liquid is achieved bycontacting the gas with the liquid while the gas passes through thepermeable sheets, so that material transfer or heat exchange can beeffected efficiently with a minimum pressure loss.

[0003] For manufacturing this X-packing, the inventor of thisapplication proposed the method described in U.S. Pat. No. 5,673,726.According to this method, as shown in FIG. 22, permeable sheets 51 inplural layers and joints 51 b of adjacent permeable sheets 51 aresimultaneously produced and a three-dimensional woven packing 50 therebyis produced.

[0004] In a case where this X-packing manufactured by the abovedescribed prior art method is used as a packing loaded in, e.g., agas-liquid mixing device, the packing 50 of FIG. 22 is erected in thedevice and liquid from a distributor is caused to flow from the top tothe bottom, i.e., in the direction of arrow A. It is, however, actuallydifficult to maintain the packing 50 strictly horizontally in the deviceby reason of an error in installation or other causes and, as a result,the threads that run crosswise of the separated portions 51 a and thejoints 51 b of the packing 50 are disposed in a somewhat inclinedrelationship to the horizontal direction. For this reason, when theoperation of the device is started and liquid is caused to flow in thedirection of the arrow A, the liquid flows concentrically along a lowerportion of the threads that run crosswise with the result thatcollection, horizontal distribution and downward redistribution of theliquid are not performed uniformly but flow of the liquid tends toconcentrate on the lower portion of the inclined threads runningcorsswise.

[0005] It is, therefore, an object of the invention to provide anX-packing capable of accurately achieving uniform collection andredistribution of liquid at joints of the X-packing.

[0006] It is another object of the invention to provide a method formanufacturing such X-packing at a low cost and in a large scale.

SUMMARY OF THE INVENTION

[0007] For achieving these objects of the invention, there is provided amethod for manufacturing a packing made of a three-dimensional net-likestructure which constitutes an internal structure of a device whichperforms material transfer, heat exchange or mixing between gases,liquids or gas and liquid, said internal structure being divided in aplurality of chambers or channels connected to one another and saidthree-dimensional net-like structure being formed by conversion anddispersion of four line elements, said method comprising steps of

[0008] (A) disposing first line elements extending in parallel at apredetermined interval in a first direction on a plane and second lineelements extending in parallel at a predetermined interval in a seconddirection which is different from the first direction on the same planein such a manner that the first line elements cross the second lineelements at a desired angle and the first and second line elements arelaid one upon the other;

[0009] (B) fixing the first line elements to the second line elements atcrossing points thereof and thereby forming a net;

[0010] (C) pressing the net to form a plurality of parallel undulatingbulging portions which bulge at alternate ones of the crossing pointscontinuously formed in the first direction and the second direction andthereby forming an undulating net;

[0011] (D) laying a second layer of the undulating net upon a firstlayer of the undulating net in such a manner that the crossing pointscontinuously formed in the first direction and the second direction ofthe first layer of the undulating net alternately come into contact withand separate from the crossing points continuously formed in the firstdirection and the second direction of the second layer of the undulatingnet and thereafter fixing together the crossing points of the firstlayer of the undulating net and the second layer of the undulating netwhich are in contact with each other; and

[0012] (E) laying a third layer of the undulating net upon the secondlayer of the undulating net in such a manner that the crossing pointscontinuously formed in the first direction and the second direction ofthe second layer of the undulating net alternately come into contactwith and separate from the crossing points continuously formed in thefirst direction and the second direction of the third layer of theundulating net and thereafter fixing together the crossing points of thesecond layer of the undulating net and the third layer of the undulatingnet which are in contact with each other; and thereafter superposing afourth, a fifth . . . and n-th (n being any integer) layer of theundulating nets in the same manner and fixing together the crossingpoints of the respective layers of the undulating nets and theimmediately lower layers of the undulating nets which are in contactwith each other.

[0013] According to the manufacturing method, a packing 1 as shown inthe schematic perspective view of FIG. 1 can be obtained. This packing 1has, as shown in the partial perspective view of FIG. 2, has a unitstructure 2 which is a combination of two quadruple pyramids which as acommon base and apexes which are directed in the opposite directions.The three-dimensional net-like structure is formed by disposing aplurality of the unit structures 2 in vertical and horizontaldirections. As will be apparent from FIG. 2, in this unit structure 2,four line elements 3 constitute four sides of the respective quadruplepyramids and respective apexes 2 a of the two quadruple pyramids andjoints 2 b of the two quadruple pyramids are formed by conversion anddispersion of four line elements. Accordingly, no element correspondingto the horizontal threads in the prior art X-packing is used at all inthis unit structure 2.

[0014] Accordingly, by using the packing 1 manufactured by the method ofthe invention in a device such as a gas-liquid contact device, liquidfrom a distributor flows in the direction of arrow B in FIG. 1 and,since no element corresponding to the horizontal threads is used in thepacking 1, the liquid which has fallen upon the top of the packing 1does not produce a drift which is caused by flow of the liquid toward alaterally lower portion even if there is an error in installing thepacking 1 in the device and, therefore, collection and downwardredistribution of the liquid at the two vertical apexes 2 a and joints 2b of the two quadruple pyramids of the unit structure 2 are performeduniformly.

[0015] For achieving the objects of the invention, there is alsoprovided a method for manufacturing a packing made of athree-dimensional net-like structure which constitutes an internalstructure of a device which performs material transfer, heat exchange ormixing between gases, liquids or gas and liquid, said internal structurebeing divided in a plurality of chambers or channels connected to oneanother and said three-dimensional net-like structure being formed byconversion and dispersion of three line elements, said methodcomprising:

[0016] (A) a step of forming a first undulating net comprising thefollowing steps (a), (b) and (c):

[0017] (a) disposing first line elements extending in parallel at apredetermined interval in a first direction on a plane and second lineelements extending in parallel at a predetermined interval in a seconddirection which is different from the first direction on the same planein such a manner that the first line elements cross the second lineelements at a desired angle and are superposed one upon the other;

[0018] (b) fixing the first line elements to the second line elements atcrossing points thereof and thereby forming a net; and

[0019] (c) pressing the net to form a plurality of parallel undulatingbulging portions and thereby forming a first undulating net in such amanner that one of the crossing points continuously formed in the firstdirection and the second direction constitutes a crossing point of thelowest level in forming of a unit three-dimensional net-like structure,a crossing point adjacent to the crossing point of the lowest levelconstitutes a crossing point of a lower side middle level in forming ofthe unit three-dimensional net-like structure, a crossing point adjacentto the crossing point of the lower side middle level constitutes acrossing point of an upper side middle level in forming of the unitthree-dimensional net-like structure, a crossing point adjacent to thecrossing point of the upper side middle level constitutes a crossingpoint of the lower side middle level in forming of the unitthree-dimensional net-like structure, a crossing point adjacent to thecrossing point of the lower side middle level constitutes a crossingpoint of the lowest level in forming of the unit three-dimensionalnet-like strucuture, and subsequent crossing points constitute crossingpoints of the respective levels in the above cycle in forming of theunit three-dimensional net-like structure;

[0020] (B) a step of forming a second undulating net comprising thefollowing steps (a), (b) and (c):

[0021] (a) disposing

[0022] first line elements extending in parallel at a predeterminedinterval in the first direction on a plane, bending at a positioncorresponding to one of the crossing points of the lower side middlelevel of the first undulating net at a predetermined angle and extendingin a third direction, bending at a position corresponding to the nextlower side middle point of the first undulating net at the predeterminedangle and extending in the second direction, bending at a positioncorresponding to the next lower side middle level of the firstundulating net at the predetermined angle and extending in the thirddirection again, and bending at a position corresponding to the nextlower side middle level of the first undulating net at the predeterminedangle and repeating the cycle of extending in the first direction, thethird direction, the second direction and the third direction, and

[0023] second line elements extending in parallel at a predeterminedinterval in the second direction on the plane, bending at a positioncorresponding to one of the crossing points of the lower side middlelevel of the first undulating net at a predetermined angle and extendingin the third direction, bending at a position corresponding to the nextlower side middle point of the first undulating net at the predeterminedangle and extending in the first direction, bending at a positioncorresponding to the next lower side middle level of the firstundulating net at the predetermined angle and extending in the thirddirection again, and bending at a position corresponding to the nextlower side middle level of the first undulating net at the predeterminedangle and repeating the cycle of extending in the second direction, thethird direction, the first direction and the third direction

[0024] in such a manner that the first line elements and the second lineelements cross each other at the desired angle in their portionsextending in the first or second direction at positions corresponding tothe crossing points of the upper side middle level of the firstundulating net and extend jointly one being laid upon the other in theirportions extending in the third direction;

[0025] (b) fixing the first line elements to the second line elements atthe respective crossing points thereof and also at joining points andseparating points of their portions extending in the third direction andthereby forming a net; and

[0026] (c) pressing the net to form a plurality of parallel undulatingbulging portions which bulge at the respective crossing points and alsoat middle positions of the portions extending in the third direction andthereby constitute the upper side middle level in forming of the unitthree-dimensional net-like structure, and thereby forming a secondundulating net;

[0027] (C) a step of forming a third undulating net comprising thefollowing steps (a), (b) and (c):

[0028] (a) disposing

[0029] first line elements extending in parallel at a predeterminedinterval in the third direction on a plane, bending at a positioncorresponding to one of the crossing points of the lower side middlelevel of the first undulating net at a predetermined angle and extendingin the second direction, bending at a position corresponding to the nextlower side middle point of the first undulating net at the predeterminedangle and extending in the third direction again, bending at a positioncorresponding to the next lower side middle level of the firstundulating net at the predetermined angle and extending in the firstdirection, and bending at a position corresponding to the next lowerside middle level of the first undulating net at the predetermined angleand repeating the cycle of extending in the third direction, the seconddirection, the third direction and the first direction, and

[0030] second line elements extending in parallel at a predeterminedinterval in the third direction on the plane, bending at a positioncorresponding to one of the crossing points of the lower side middlelevel of the first undulating net at a predetermined angle and extendingin the first direction, bending at a position corresponding to the nextlower side middle point of the first undulating net at the predeterminedangle and extending in the third direction again, bending at a positioncorresponding to the next lower side middle level of the firstundulating net at the predetermined angle and extending in the seconddirection, and bending at a position corresponding to the next lowerside middle level of the first undulating net at the predetermined angleand repeating the cycle of extending in the third direction, firstdirection, the third direction and the second direction

[0031] in such a manner that the first line elements and the second lineelements cross each other at the desired angle in their portionsextending in the first or second direction at positions corresponding tomiddle positions of the portions extending in the third direction of thesecond undulating net and extend jointly one being laid upon the otherin their portions extending in the third direction;

[0032] (b) fixing the first line elements to the second line elements atthe crossing points thereof and also at joining points and separatingpoints of their portions extending in the third direction and therebyforming a net; and

[0033] (c) pressing the net to form a plurality of parallel undulatingbulging portions which bulge at the respective joining and separatingpoints of the portions extending in the third direction and therebyconstitute the highest level in forming of the unit three-dimensionalnet-like structure, and thereby forming a third undulating net;

[0034] (D) a step of laying the second undulating net upon the firstundulating net in such a manner that the crossing points of the secondundulating net come into contact with the crossing points of the uppermiddle level of the first undulating net, the joining points and theseparating points of the portions extending in the third direction ofthe second undulating net come into contact with the crossing points ofthe lower middle level of the first undulating net, and the undulatingbulging portions at the middle positions of the portions extending inthe third direction of the second undulating net are separated from thecrossing points of the lowest level of the first undulating net and formthe upper middle level of the unit three-dimensional net-like structure;

[0035] (E) a step of laying the third undulating net upon the secondundulating net in such a manner that the crossing points of the thirdundulating net come into contact with the undulating bulging portions atthe middle positions of the portions extending in the third direction ofthe second undulating net, the portions extending in the third directionof the third undulating net come into contact, at their middlepositions, with the crossing points of the second undulating net, andthe undulating bulging portions at the joining points and the separatingpoints of the portions extending in the third direction of the thirdundulating net are separated from the second undulating net and form thehighest level of the unit three-dimensional net-like structure; and

[0036] (F) a step of fixing the first undulating net, the secondundulating net and the third undulating net together at necessary pointsamong points of contact thereof.

[0037] According to this manufacturing method, a packing 30 as shown inthe schematic perspective view of FIG. 3 can be obtained. This packing30 has, as shown in the partial perspective view of FIG. 4, a unitstructure 32 which is a combination of three triangular pyramids 33 eachhaving an apex 33 a and three sides 33 b and three triangular pyramids34 each having an apex 34 a directed in the opposite direction to theapex 33 a and three sides 34 b. The three-dimensional net-like structureis formed by disposing a plurality of the unit structures 32 in verticaland horizontal directions.

[0038] In the unit structure 32, the respective sides 33 b and 34 b areformed with line elements. More specifically, three line elementsconstitute the three sides 33 b and 34 b of the triangular pyramids 33and 34 and the apexes 33 a and 34 a of the respective triangularpyramids and joints 35 of the sides of the respective triangularpyramids are formed by conversion and dispersion of three line elements.In this unit structure 32 either, no element corresponding to thehorizontal threads is provided at all and, therefore, the same effect asthe one described above with respect to the unit structure 2 can beachieved. That is, liquid flows in the direction of arrow C in FIG. 3and collection and downward redistribution of the liquid at the apexes33 a and 34 a and the joints 35 of the triangular pyramids 33 and 34 ofthe unit structure 32 are performed uniformly.

[0039] The present invention can be applied not only to the columpacking used in devices such as a gas-liquid mixing device but also tomanufactring of other three-dimensional net-like structure such as onesused for a mist eliminator, a multi-layer filtering film and aggregate.

[0040] In one aspect of the invention, there is provided a method formanufacturing a three-dimensional net-like structure including a misteliminator and a multi-layer filtering film formed by conversion anddispersion of four line elements, said method comprising steps of:

[0041] (A) disposing first line elements extending in parallel at apredetermined interval in a first direction on a plane and second lineelements extending in parallel at a predetermined interval in a seconddirection which is different from the first direction on the same planein such a manner that the first line elements cross the second lineelements at a desired angle and the first and second line elements arelaid one upon the other;

[0042] (B) fixing the first line elements to the second line elements atcrossing points thereof and thereby forming a net;

[0043] (C) pressing the net to form a plurality of parallel undulatingbulging portions which bulge at alternate ones of the crossing pointscontinuously formed in the first direction and the second direction andthereby forming an undulating net;

[0044] (D) laying a second layer of the undulating net upon a firstlayer of the undulating net in such a manner that the crossing pointscontinuously formed in the first direction and the second direction ofthe first layer of the undulating net alternately come into contact withand separate from the crossing points continuously formed in the firstdirection and the second direction of the second layer of the undulatingnet and thereafter fixing together the crossing points of the firstlayer of the undulating net and the second layer of the undulating netwhich are in contact with each other; and

[0045] (E) laying a third layer of the undulating net upon the secondlayer of the undulating net in such a manner that the crossing pointscontinuously formed in the first direction and the second direction ofthe second layer of the undulating net alternately come into contactwith and separate from the crossing points continuously formed in thefirst direction and the second direction of the third layer of theundulating net and thereafter fixing together the crossing points of thesecond layer of the undulating net and the third layer of the undulatingnet which are in contact with each other; and thereafter superposing afourth, a fifth . . . and n-th (n being any integer) layer of theundulating nets in the same manner and fixing together the crossingpoints of the respective layers of the undulating nets and theimmediately lower layers of the undulating nets which are in contactwith each other.

[0046] In another aspect of the invention, there is provided a methodfor manufacturing a three-dimensional net-like structure including amist eliminator and a multi-layer filtering film formed by conversionand dispersion of three line elements, said method comprising:

[0047] (A) a step of forming a first undulating net comprising thefollowing steps (a), (b) and (c):

[0048] (a) disposing first line elements extending in parallel at apredetermined interval in a first direction on a plane and second lineelements extending in parallel at a predetermined interval in a seconddirection which is different from the first direction on the same planein such a manner that the first line elements cross the second lineelements at a desired angle and are superposed one upon the other;

[0049] (b) fixing the first line elements to the second line elements atcrossing points thereof and thereby forming a net; and

[0050] (c) pressing the net to form a plurality of parallel undulatingbulging portions and thereby forming a first undulating net in such amanner that one of the crossing points continuously formed in the firstdirection and the second direction constitutes a crossing point of thelowest level in forming of a unit three-dimensional net-like structure,a crossing point adjacent to the crossing point of the lowest levelconstitutes a crossing point of a lower side middle level in forming ofthe unit three-dimensional net-like structure, a crossing point adjacentto the crossing point of the lower side middle level constitutes acrossing point of an upper side middle level in forming of the unitthree-dimensional net-like structure, a crossing point adjacent to thecrossing point of the upper side middle level constitutes a crossingpoint of the lower side middle level in forming of the unitthree-dimensional net-like structure, a crossing point adjacent to thecrossing point of the lower side middle level constitutes a crossingpoint of the lowest level in forming of the unit three-dimensionalnet-like strucuture, and subsequent crossing points constitute crossingpoints of the respective levels in the above cycle in forming of theunit three-dimensional net-like structure;

[0051] (B) a step of forming a second undulating net comprising thefollowing steps (a), (b) and (c):

[0052] (a) disposing

[0053] first line elements extending in parallel at a predeterminedinterval in the first direction on a plane, bending at a positioncorresponding to one of the crossing points of the lower side middlelevel of the first undulating net at a predetermined angle and extendingin a third direction, bending at a position corresponding to the nextlower side middle point of the first undulating net at the predeterminedangle and extending in the second direction, bending at a positioncorresponding to the next lower side middle level of the firstundulating net at the predetermined angle and extending in the thirddirection again, and bending at a position corresponding to the nextlower side middle level of the first undulating net at the predeterminedangle and repeating the cycle of extending in the first direction, thethird direction, the second direction and the third direction, and

[0054] second line elements extending in parallel at a predeterminedinterval in the second direction on the plane, bending at a positioncorresponding to one of the crossing points of the lower side middlelevel of the first undulating net at a predetermined angle and extendingin the third direction, bending at a position corresponding to the nextlower side middle point of the first undulating net at the predeterminedangle and extending in the first direction, bending at a positioncorresponding to the next lower side middle level of the firstundulating net at the predetermined angle and extending in the thirddirection again, and bending at a position corresponding to the nextlower side middle level of the first undulating net at the predeterminedangle and repeating the cycle of extending in the second direction, thethird direction, the first direction and the third direction

[0055] in such a manner that the first line elements and the second lineelements cross each other at the desired angle in their portionsextending in the first or second direction at positions corresponding tothe crossing points of the upper side middle level of the firstundulating net and extend jointly one being laid upon the other in theirportions extending in the third direction;

[0056] (b) fixing the first line elements to the second line elements atthe respective crossing points thereof and also at joining points andseparating points of their portions extending in the third direction andthereby forming a net; and

[0057] (c) pressing the net to form a plurality of parallel undulatingbulging portions which bulge at the respective crossing points and alsoat middle positions of the portions extending in the third direction andthereby constitute the upper side middle level in forming of the unitthree-dimensional net-like structure, and thereby forming a secondundulating net;

[0058] (C) a step of forming a third undulating net comprising thefollowing steps (a), (b) and (c):

[0059] (a) disposing

[0060] first line elements extending in parallel at a predeterminedinterval in the third direction on a plane, bending at a positioncorresponding to one of the crossing points of the lower side middlelevel of the first undulating net at a predetermined angle and extendingin the second direction, bending at a position corresponding to the nextlower side middle point of the first undulating net at the predeterminedangle and extending in the third direction again, bending at a positioncorresponding to the next lower side middle level of the firstundulating net at the predetermined angle and extending in the firstdirection, and bending at a position corresponding to the next lowerside middle level of the first undulating net at the predetermined angleand repeating the cycle of extending in the third direction, the seconddirection, the third direction and the first direction, and

[0061] second line elements extending in parallel at a predeterminedinterval in the third direction on the plane, bending at a positioncorresponding to one of the crossing points of the lower side middlelevel of the first undulating net at a predetermined angle and extendingin the first direction, bending at a position corresponding to the nextlower side middle point of the first undulating net at the predeterminedangle and extending in the third direction again, bending at a positioncorresponding to the next lower side middle level of the firstundulating net at the predetermined angle and extending in the seconddirection, and bending at a position corresponding to the next lowerside middle level of the first undulating net at the predetermined angleand repeating the cycle of extending in the third direction, firstdirection, the third direction and the second direction

[0062] in such a manner that the first line elements and the second lineelements cross each other at the desired angle in their portionsextending in the first or second direction at positions corresponding tomiddle positions of the portions extending in the third direction of thesecond undulating net and extend jointly one being laid upon the otherin their portions extending in the third direction;

[0063] (b) fixing the first line elements to the second line elements atthe crossing points thereof and also at joining points and separatingpoints of their portions extending in the third direction and therebyforming a net; and

[0064] (c) pressing the net to form a plurality of parallel undulatingbulging portions which bulge at the respective joining and separatingpoints of the portions extending in the third direction and therebyconstitute the highest level in forming of the unit three-dimensionalnet-like structure, and thereby forming a third undulating net;

[0065] (D) a step of laying the second undulating net upon the firstundulating net in such a manner that the crossing points of the secondundulating net come into contact with the crossing points of the uppermiddle level of the first undulating net, the joining points and theseparating points of the portions extending in the third direction ofthe second undulating net come into contact with the crossing points ofthe lower middle level of the first undulating net, and the undulatingbulging portions at the middle positions of the portions extending inthe third direction of the second undulating net are separated from thecrossing points of the lowest level of the first undulating net and formthe upper middle level of the unit three-dimensional net-like structure;

[0066] (E) a step of laying the third undulating net upon the secondundulating net in such a manner that the crossing points of the thirdundulating net come into contact with the undulating bulging portions atthe middle positions of the portions extending in the third direction ofthe second undulating net, the portions extending in the third directionof the third undulating net come into contact, at their middlepositions, with the crossing points of the second undulating net, andthe undulating bulging portions at the joining points and the separatingpoints of the portions extending in the third direction of the thirdundulating net are separated from the second undulating net and form thehighest level of the unit three-dimensional net-like structure; and

[0067] (F) a step of fixing the first undulating net, the secondundulating net and the third undulating net together at necessary pointsamong points of contact thereof.

[0068] In another aspect of the invention, there is provided a packingmade of a three-dimensional net-like structure which constitutes aninternal structure of a device which performs material transfer, heatexchange or mixing between gases, liquids or gas and liquid, saidinternal structure being divided in a plurality of chambers or channelsconnected to one another and said three-dimensional net-like structurebeing formed by conversion and dispersion of four line elements whereina converging portion of the four line elements is formed by mutualcontact of undulating nets having parallel undulating bulging portionsat necessary portions.

[0069] In another aspect of the invention, there is provided a packingmade of a three-dimensional net-like structure which constitutes aninternal structure of a device which performs material transfer, heatexchange or mixing between gases, liquids or gas and liquid, saidinternal structure being divided in a plurality of chambers or channelsconnected to one another and said three-dimensional net-like structurebeing formed by conversion and dispersion of three line elements whereina converging portion of the three line elements is formed by mutualcontact of undulating nets having parallel undulating bulging portionsat necessary portions.

[0070] In another aspect of the invention, there is provided athree-dimensional net-like structure including a mist eliminator and amulti-layer filtering film formed by conversion and dispersion of fourline elements wherein a converging portion of the four line elements isformed by mutual contact of undulating nets having parallel undulatingbulging portions at necessary portions.

[0071] In still another aspect of the invention, there is provided athree-dimensional net-like structure including a mist eliminator and amulti-layer filtering film formed by conversion and dispersion of threeline elements wherein a converging portion of the three line elements isformed by mutual contact of undulating nets having parallel undulatingbulging portions at necessary portions.

[0072] Preferred embodiments of the invention will be described belowwith reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0073] In the accompanying drawings,

[0074]FIG. 1 is a schematic perspective view showing an example of thethree-dimensional net-like structure of the invention;

[0075]FIG. 2 is a perspective view showing a unit structure of theexample;

[0076]FIG. 3 is a schematic perspective view showing another example ofthe three-dimensional net-like structure;

[0077]FIG. 4 is a perspective view showing a unit structure of theexample;

[0078]FIG. 5 is a plan view showing an example of a line element placingtable;

[0079]FIG. 6 is a view showing crossing of first line elements andsecond line elements;

[0080]FIG. 7 is a view showing fixing of the first line elements and thesecond line elements together;

[0081]FIG. 8 is a front view of a mold with its central portion beingomitted;

[0082]FIG. 9 is a partial plan view of this mold;

[0083]FIG. 10A is a side view of the mold;

[0084]FIGS. 10B to 10D are views showing the process of forming anundulating net by this mold;

[0085]FIG. 11A is a plan view of a laying table for laying undulatingnets one upon another;

[0086]FIG. 11B is a side view of the laying table;

[0087]FIG. 12 is a side view of the laying table showing laying of asecond undulating net on a first undulating net;

[0088]FIG. 13 is a side view of the laying table showing laying of athird undulating net on the second undulating net;

[0089]FIG. 14 is a side view of a lower mold of a mold used for a secondembodiment of the manufacturing method of the invention;

[0090]FIG. 15A is a front view of a first undulating net used in thesecond embodiment;

[0091]FIG. 15B is a side view of the first undulating net;

[0092]FIG. 16 is a plan view of a line element placing table showingforming of a second undulating net in the second embodiment;

[0093]FIG. 17A is a front view of the second undulating net of thesecond embodiment;

[0094]FIG. 17B is a side view of the second undulating net of the secondembodiment;

[0095]FIG. 18 is a plan view of a line element placing table showingforming of a third undulating net of the second embodiment;

[0096]FIG. 19A is a front view of the third undulating net of the secondembodiment;

[0097]FIG. 19B is a side view of the third undulating net of the secondembodiment;

[0098]FIGS. 20A and 20B show laying of the second undulating net on thefirst undulating net in the second embodiment in which

[0099]FIG. 20A is a front view of the undulating nets and

[0100]FIG. 20B is a side view of the undulating nets;

[0101]FIGS. 21A to 20C show laying of the third undulating net on thefirst and second undulating nets in the second embodiment in which

[0102]FIG. 21A is a front view of the nets,

[0103]FIG. 21B is a side view thereof and

[0104]FIG. 21C is a plan view thereof;

[0105]FIG. 22 is a perspective view showing a prior art method formanufacturing an X-packing; and

[0106]FIG. 23 is a partial plan view showing laying state of FIG. 13.

DESCRIPTION OF PREFERRED EMBODIMENTS

[0107] Embodiment 1

[0108] This embodiment relates to a method for manufacturing thethree-dimensional net-like structure shown in FIGS. 1 and 2.

[0109] (1) Step of Disposing Line Elements

[0110] A line element used in the manufacturing method of the inventionmay be made of metal or plastic. There is no particular limitation inthe material used for the line element and wire, twine or monofilamentmay be used as the line element. Since the line element is formed to anundulating net by pressing, the material for the line element must becapable of plastic deformation and have sufficient rigidity to maintainthe undulating shape after pressing.

[0111] The line element may be made of a monofilament or a single pieceof wire but a line element made of wire or twine which is made bytwisting thin steel lines or plastic lines is preferable because liquidflows along the space between the lines which constitute the wire ortwine due to the capillary action and thereby enhance transfer of theliquid. In the present embodiment, seven steel lines each having adiameter of 0.1 mm are twisted together to form a single steel wire andtwo of this steel wire are further twisted to a single wire and thiswire is used as the line element 3.

[0112] This line element 3 is disposed on a line element placing table 4shown in the plan view of FIG. 5. In the plan view, line elementengaging pins 5 are provided at a predetermined interval in the fouredge portions of the line element placing table 4. The line element 3wound about a drum (not shown) is unwound from the drum and, as shown inFIG. 5 by way of example, is guided by a pin 5-1 provided in the leftupper corner as viewed in FIG. 5 and thereafter is disposed over theentire surface of the line elements placing table 4, guided by pins 5-2,5-3, 5-4, 5-5 and so on and extending in the order of arrows D, E, F, Getc.

[0113] Thus, first line elements 2 a which extend in parallel at apredetermined interval in a first direction X on a plane and second lineelements 3 b which extend in parallel at a predetermined interval in asecond direction Y which is different from the first direction X aredisposed in such a manner that the first line elements 3 a cross thesecond line elements 3 b at a desired angle a and the first and secondline elements 3 a and 3 b are laid one upon the other as shown in FIG.6.

[0114] (2) Step of Fixing the First Line Elements to the Second LineElements at Respective Crossing Points

[0115] The first line elements 3 a and the second line elements 3 b thusdisposed are spot-welded to each other at respective crossing points 6by a known spot wedling machine as shown in FIG. 7 and a net 7 isthereby formed.

[0116] (3) Step of Cutting Off a Net

[0117] This net 7 is removed from the line element placing table 4 andcut into a predetermined size.

[0118] (4) Step of Forming of an Undulating Net

[0119] Then, the net 7 is pressed by a mold 8 shown in FIGS. 8 to 10 toform an undulating net.

[0120]FIG. 8 is a front view of the mold 8 with a part thereof beingomitted, FIG. 9 is a partial plan view of the mold 8 and FIG. 10A is aside view of the mold 8. In the mold 8, an upper mold table 9 has slideportions 12, 12 which are slidably engaged on a pair of slide shafts 11,11 erected upwardly from a lower mold table 10 and thereby can slidevertically along the slide shafts 11, 11. The upper mold table 9 has anupper mold 13 fixed thereon and the lower mold table 10 has a lower mold14 fixed thereon.

[0121] The lower mold 14 has a row of positioning pins 15 which areerected ahead of the upper mold 13 in the feeding direction of the net7. The upper mold 13 and the lower mold 14 are formed on the lowersurface of the upper mold 13 and the upper surface of the lower mold 14with waveforms 13 a and 14 a which are to be imparted to the undulatingnet. These waveforms are such that crossing points 6 which are formedcontinuously in the first direction X and the second direction Y of thenet 7 bulge alternately to form parallel undulating bulging portions.

[0122] For forming the net 7 to the undulating net, as shown in FIG. 9and FIG. 10A, the net 7 is first positioned on the lower mold 14 withthe upper mold 13 being located above the lower mold 14. The positioningis effected by inserting the positioning pins 15 in rhombic spaces ofthe net 7 formed by adjacent crossings 6 in the forward end portion ofthe net 7 in the feeding direction of the net 7.

[0123] Then, manually or by driving the upper mold 13 by a drive unit(not shown), the upper mold 13 is lowered toward the lower mold 14 topress the net 7 between the upper mold 13 and the lower mold 14 andthereby impart the waveform as shown in FIG. 10B.

[0124] Then, as shown in FIG. 10C, the upper mold 13 is lifted, the net7 is dieengaged from the positioning pins 15 and fed in the direction ofarrow J so as to place a flat portion of the net 7 which has not beenimparted with the waveform on the portion of the lower mold 14 havingthe waveform 14 a. The net 7 is positioned again by inserting thepositioning pins 15 in the rear end portion of the portion of the net 7in which the waveform has been imparted.

[0125] Then, as shown in FIG. 10D, the upper mold 13 is lowered again topress the net 7 and thereby impart the waveform to the net 7.

[0126] By repeating the above described operations, parallel undulatingbulging portions in which the crossing points 6 formed continuously inthe first direction X and the second direction Y bulge alternately aresequentially formed and the undulating net thereby is produced.

[0127] (5) Step of Laying of the Second Layer of the Undulating Net onthe First Layer of the Undulating Net and Fixing of the Two LayersTogether

[0128] Plural layers of the undulating nets thus formed are sequentiallylaid one upon another on a laying table 16 shown in FIGS. 11 to 13 andFIG. 23. FIG. 1A is a plan view of the laying talbe 16, FIG. 11B is aside view thereof, FIG. 12 is a partial side section showing a manner oflaying a second layer undulating net 17-2 on a first layer undulatingnet 17-1 and fixing them together, FIG. 13 is a partial side sectionshowing a manner of laying a third layer undulating net 17-3 on thesecond layer undulating net 17-2 and fixing them together, and FIG. 23is a partial plan view showing the laying state of FIG. 13.

[0129] The laying table 16 is formed on the upper surface thereof with awaveform 16 a which is the same as the shape of the parallel undulatingbulging portions of the net which are formed by alternate bulging of thecrossing points 6 which are formed continuously in the first direction Xand the second direction Y. In the left and right end portions as viewedin FIG. 11 of the laying table 16 are provided positioning pins 18 forpositioning the undulating net 17. Reference character 19 designatesguide pins for holding electrode pins.

[0130] In FIGS. 12 and 13, only a part of an electrode 21 of aspot-welding machine is illustrated and illustration of the otherportion of the spot-welding machine is omitted.

[0131] The first layer undulating net 17-1 is positioned on the layingtable 16 in such a manner that the positioning pins 18 are inserted inrhombic spaces formed between adjacent crossing points 6 of theundulating net 17-1 and, as shown in FIG. 12, the waveform of the firstlayer undulating net 17-1 conforms with the waveform of the laying table16.

[0132] Then, as shown in FIG. 12, electrode pins 20 are disposed inrecessed portions of the first layer undulating net 17-1 and then thesecond layer undulating net 17-2 is laid on the first layer undulatingnet 17-1 in such a manner that the crossing points which are formedocontinuously in the first direction X and the second direction Y of thefirst layer undulating net 17-1 alternately come into contact with andare separated from the crossing points which are formed continuously inthe first direction X and the second direction Y of the second layerundulating net 17-2. Then, the crossing points which are in contact witheach other of the first layer undulating net 17-1 and the second layerundulating net 17-2 are spot-welded by the spot welding machine 21.

[0133] (6) Step of Laying of the Third to n-th Layer Undulating Nets andFixing Thereof.

[0134] After disposing electrode pins 22 for spot-welding in recessedportions of the second layer undulating net 17-2, the third layerundulating net 17-3 is laid on the second layer undulating net 17-2 insuch a manner that the crossing points which are formed ocontinuously inthe first direction X and the second direction Y of the second layerundulating net 17-2 alternately come into contact with and are separatedfrom the crossing points which are formed continuously in the firstdirection X and the second direction Y of the third layer undulating net17-3. Then, the crossing points which are in contact with each other ofthe second layer undulating net 17-2 and the third layer undulating net17-3 are spot-welded. Subsequently, fourth layer, fifth layer, . . .n-th layer (n being any integer) undulating nets are laid in said orderin the same manner as described above and crossing points which are incontact with each other between immediately adjacent undulating nets arespot-welded. Thus, the packing 1 made of the three-dimensional net-likestructure as shown in FIG. 1 is formed.

[0135] Second Embodiment

[0136] Step of Forming a First Undulating Net

[0137] (a) Step of Disposing Line Elements

[0138] The same wire as used in the embodiment 1 is used as the lineelement of the embodiment 2. This line element is disposed over the lineelement placing table 4 shown in FIG. 5. The manner of disposing theline element is similar to that of the embodiment 1, namely first lineelements 3 a which extend in parallel at a predetermined interval in afirst direction X on a plane and second line elements 3 b which extendin parallel at a predetermined interval in a second direction Y which isdifferent from the first direction X are disposed in such a manner thatthe first line elements 3 a cross the second line elements 3 b at adesired angle α and the first and second line elements 3 a and 3 b arelaid one upon the other as shown in FIG. 6.

[0139] (b) Step of Fixing the First Line Elements to the Second LineElements at Respective Crossing Points

[0140] The first line elements 3 a and the second line elements 3 b thusdisposed are spot-welded to each other at respective crossing points 6by a known spot welding machine as shown in FIG. 7 and a net 7 isthereby formed.

[0141] (c) Step of Cutting Off a Net

[0142] This net 7 is removed from the line element placing table 4 andcut into a predetermined size.

[0143] (d) Step of Forming of an Undulating Net

[0144] Then, the net 7 is pressed by a mold 8 to form a first undulatingnet. This mold 8 is of a construction similar to the mold shown in FIGS.8 to 10 but the waveforms which are formed on the lower surface of theupper mold and the upper surface of the lower mold are different fromthose shown in FIGS. 8 to 10. That is, as will be seen in an example ofthe waveform on the lower mold 24 shown in the side view of FIG. 14, thewaveforms are such that crossing points formed continuously in the firstdirection X and the second direction Y sequentially constitute thelowest level 24 a, lower side middle level 24 b and upper side middlelevel 24 c.

[0145] The net 7 is disposed on the lower mold 24 shown in FIG. 14 andthe upper mold (not shown) having a waveform which conforms with the thewaveform of the lower mold 24 is lowered to press the net 7. Thus, asshown in the partial front view of FIG. 15A and the side view of FIG.15B, a plurality of parallel undulating bulging portions are formed andthereby a first undulating net 25-1 is formed in such a manner that oneof the crossing points continuously formed in the first direction andthe second direction constitutes a crossing point 24 a (shown by a blacksquare) of the lowest level in forming of a unit three-dimensionalnet-like structure, a crossing point adjacent to the crossing point 24 aof the lowest level constitutes a crossing point 24 b (shown by a blackcircle) of a lower side middle level in forming of the unitthree-dimensional net-like structure, a crossing point adjacent to thecrossing point 24 b of the lower side middle level constitutes acrossing point 24 c (shown by a white circle) of an upper side middlelevel in forming of the unit three-dimensional net-like structure, acrossing point adjacent to the crossing point 24 c of the upper sidemiddle level constitutes a crossing point 24 b of the lower side middlelevel in forming of the unit three-dimensional net-like structure, acrossing point adjacent to the crossing point 24 b of the lower sidemiddle level constitutes a crossing point 24 a of the lowest level informing of the unit three-dimensional net-like strucuture, andsubsequent crossing points constitute crossing points 24 a, 24 b and 24c of the respective levels in the above cycle in forming of the unitthree-dimensional net-like structure.

[0146] (2) Step of Forming a Second Undulating Net

[0147] (a) Step of Disposing Line Elements

[0148] Wire which is of the same structure as the line elements of thefirst undulating net 25-1 is used as the line element of the secondundulating net and this line element is disposed over the line elementplacing table. This line element placing table is similar to the lineelement placing table 4 but is different from the line element placingtable 4 in that, as shown in FIG. 16, pairs of guide pins 26 for guidingthe line elements are provided at a predetermined interval on the table.The line elements are disposed in the following manner.

[0149] In FIG. 16, first line elements 27 extend in parallel at apredetermined interval in the first direction X on the line elementplacing table, bend at a position 24 b corresponding to the crossingpoint 24 b of the lower side middle level of the first undulating net25-1 at a predetermined angle, passing between a pair of guide pins 26and being guided by them, and extend in a third direction Z. The firstline elements 27 then bend at a position 24 b corresponding to the nextcrossing point 24 b of the lower side middle point of the firstundulating net 25-1 at the predetermined angle, guided by the pair ofguide pins 26, and extend in the second direction Y. The first lineelements then bend at a position 24 b corresponding to the crossingpoint 24 b of the next lower side middle level of the first undulatingnet 25-1 at the predetermined angle, guided by the pair of guide pins26, and extend in the third direction Z again. The first line elementsthen bend at a position 24 b corresponding to the crossing point 24 b ofthe next lower side middle level of the first undulating net 25-1 at thepredetermined angle and repeat the cycle of extending in the firstdirection X, the third direction Z, the second direction Y and the thirddirection Z.

[0150] Second line elements 28 extend in parallel at a predeterminedinterval in the second direction Y on the line element placing table,bend at a position 24 b corresponding to the crossing point 24 b of thelower side middle level of the first undulating net 25-1 at apredetermined angle, guided by the pair of guide pins 26, and extend inthe third direction Z. The second line elements then bend at a position24 b corresponding to the crossing point 24 b of the next lower sidemiddle point of the first undulating net 25-1 at the predeterminedangle, guided by the pair of guide pins 26, and extend in the firstdirection X. The second line elements then bend at a position 24 bcorresponding to the crossing point 24 b of the next lower side middlelevel of the first undulating net 25-1 at the predetermined angle,guided by the pair of guide pins 26, and extend in the third direction Zagain. The second line elements then bend at a position 24 bcorresponding to the crossing point 25 b of the next lower side middlelevel of the first undulating net 25-1 at the predetermined angle,guided by the pair of guide pins 25, and repeat the cycle of extendingin the second direction Y, the third direction Z, the first direction Xand the third direction Z.

[0151] The first line elements 27 and the second line elements 28 aredisposed in such a manner that the first line elements 27 and the secondline elements 28 cross each other at the desired angle in their portionsextending in the first direction X or the second direction Y atpositions 24 c corresponding to the crossing points 24 c of the upperside middle level of the first undulating net 25-1 and extend jointlyone being laid upon the other in their portions extending in the thirddirection Z.

[0152] (b) Step of Fixing the First Line Elements to the Second LineElements

[0153] The first line elements 27 are fixed to the second line elements28 by spot welding at the respective crossing points thereof and also atjoining points and separating points of their portions extending in thethird direction Z and thereby a net 29 is formed.

[0154] (c) Step of Cutting Off of the Net

[0155] This net 29 is removed from the line element placing table andcut to a predetermined size.

[0156] (d) Step of Forming an Undulating Net

[0157] By pressing the net 29 using a mold 8 shown in FIGS. 8 to 10, aplurality of parallel undulating bulging portions which bulge at therespective crossing points and also at middle positions of the portionsextending in the third direction Z and thereby constitute the upper sidemiddle level 24 c in forming of the unit three-dimensional net-likestructure are formed and a second undulating net 25-2 thereby is formed.

[0158]FIG. 17A is a partial front view of this second undulating net25-2 and FIG. 17B is a side view thereof. In the same manner as in FIG.15, the white circle in FIGS. 17A and 17B designates the upper sidemiddle level 24 c and the black circle the lower side middle level 24 b.

[0159] In FIG. 16, one of the two joining line elements extending in thedirection Z is illustrated on the upper side and the other on the lowerside whereas in FIG. 17, the two line elements extending in thedirection Z are shown in the state in which the two line elements aredisposed in parallel to each other for convenience of illustration.

[0160] (3) Step of Forming a Third Undulating Net

[0161] (a) Step of Disposing Line Elements

[0162] Wire which is of the same structure as the line elements of thefirst and second undulating nets 25-1 and 25-2 is used as the lineelement of the third undulating net and this line element is disposed onthe line element placing table used for forming of the net 29 of thesecond undulating net 25-2.

[0163] In FIG. 18, first line elements 40 extend in parallel at apredetermined interval in the third direction Z on the line elementplacing table, bend at a position 24 b corresponding to the crossingpoint 24 b of the lower side middle level of the first undulating net25-1 at a predetermined angle, guided by the pair of guide pins 26, andextend in the second direction Y. The first line element then bend at aposition 24 b corresponding to the crossing point 24 b of the next lowerside middle point of the first undulating net 25-1 at the predeterminedangle, guided by the pair of guide pins 26, and extend in the thirddirection Z again. Then the first line elements bend at a position 24 bcorresponding to the crossing point 24 b of the next lower side middlelevel of the first undulating net 25-1 at the predetermined angle,guided by the pair of guide pins 26, and extend in the first directionX. The first line element then bend at a position 24 b corresponding tothe crossing point 24 b of the next lower side middle level of the firstundulating net 25-1 at the predetermined angle and repeat the cycle ofextending in the third direction Z, the second direction Y, the thirddirection Z and the first direction X.

[0164] Second line elements 41 extend in parallel at a predeterminedinterval in the third direction Z on the line element placing table,bend at a position 24 b corresponding to the crossing point 24 b of thelower side middle level of the first undulating net 25-1 at apredetermined angle and extend in the first direction X. The second lineelements then bend at a position 24 b corresponding to the crossingpoint 24 b of the next lower side middle point of the first undulatingnet 25-1 at the predetermined angle and extend in the third directionagain Z. The second line elements then bend at a position 24 bcorresponding to the crossing point 24 b of the next lower side middlelevel of the first undulating net 25-1 at the predetermined angle andextend in the second direction Y The second line elements then bend at aposition 24 b corresponding to the crossing point 24 b of the next lowerside middle level of the first undulating net 25-1 at the predeterminedangle and repeat the cycle of extending in the third direction Z, firstdirection X, the third direction Z and the second direction Y.

[0165] The first line elements 40 and the second line elements 41 aredisposed in such a manner that the first line elements 40 and the secondline elements 41 cross each other at the desired angle in their portionsextending in the first direction X or second direction Y at positionscorresponding to middle positions of the portions extending in the thirddirection Z of the second undulating net 25-2 and extend jointly onebeing laid upon the other in their portions extending in the thirddirection Z.

[0166] (b) Step of Fixing the First Line Elements to the Second LineElements

[0167] The first line elements 40 are fixed to the second line elements41 by spot welding at the crossing points thereof and also at joiningpoints and separating points of their portions extending in the thirddirection Z and a net 42 thereby is formed.

[0168] (c) Step of Cutting Off of the Net

[0169] The net 42 is removed from the line element placing table and cutto a predetermined size.

[0170] (d) Step of Forming of an Undulating Net

[0171] By pressing the net 42 by the mold 8 shown in FIGS. 8 to 10, aplurality of parallel undulating bulging portions which bulge at therespective joining and separating points of the portions extending inthe third direction Z and thereby constitute the highest level informing of the unit three-dimensional net-like structure are formed, andthereby a third undulating net 25-3 is formed.

[0172]FIG. 19A is a partial front view of the third undulating net 25-3and FIG. 19B is a side view thereof. In the same manner as in FIGS. 15and 17, the white circle designates the upper side middle point 24 c andthe white square the highest level 24 d of the unit three-dimensionalnet-like structure in the forming process.

[0173] In FIG. 18, one of the two joining line elements extending in thedirection Z is illustrated on the upper side and the other on the lowerside whereas in FIG. 19, the two line elements extending in thedirection Z are shown in the state in which the two line elements aredisposed in parallel to each other for convenience of illustration.

[0174] (e) Step of Laying the Second Undulating Net Upon the FirstUndulating Net

[0175] On a laying table which is of a similar construction to thelaying table 16 shown in FIG. 11 formed on the entire upper surfacethereof with the same waveform as the waveform of FIG. 14, the firstundulating net 25-1 is placed in such a manner that its crossing point24 a of the lowest level, crossing points 24 b of the lower side middlelevel and crossing points 24 c of the upper side middle level conformwith the lowest level, lower side middle level and upper side middlelevel of the corresponding waveform in the laying table.

[0176] The manner of laying the second undulating net 25-2 on the firstundulating net 25-1 is shown in the partial front view of FIG. 20A andthe side view of FIG. 20B. In FIGS. 20A and 20B, the undulating net 25-1is shown by a solid line and the undulating net 25-2 is shown in abroken line.

[0177] The second undulating net 25-2 is laid upon the first undulatingnet 251 in such a manner that the crossing points of the secondundulating net 25-1 come into contact with the crossing points 24 c ofthe upper side middle level of the first undulating net, 25-1, thejoining points and the separating points of the portions extending inthe third direction Z of the second undulating net 25-2 come intocontact with the crossing points 24 b of the lower side middle level ofthe first undulating net 25-1, and the undulating bulging portions atthe middle positions of the portions extending in the third direction Zof the second undulating net 25-2 are separated from the crossing points24 a of the lowest level of the first undulating net 25-1 and form theupper side middle level 24 c of the unit three-dimensional net-likestructure;

[0178] (f) Step of Laying the Third Undulating Net Upon the SecondUndulating Net

[0179]FIG. 21 shows a manner of laying the third undulating net 25-3upon the second undulating net 25-2. FIG. 21A is a front view thereof,FIG. 21B is a side view thereof and FIG. 21C is a top plan view thereof.In FIG. 21, the first undulating net 25-1 and the second undulating net25-2 are shown by solid lines and the third undulating net 25-3 is shownby a broken line.

[0180] The third undulating net 25-3 is laid upon the second undulatingnet 25-2 in such a manner that the crossing points of the thirdundulating net 253 come into contact with the undulating bulgingportions at the middle positions of the portions extending in the thirddirection Z of the second undulating net 25-2, the portions extending inthe third direction Z of the third undulating net 25-3 come intocontact, at their middle positions, with the crossing points of thesecond undulating net 25-2, and the undulating bulging portions at thejoining points and the separating points of the portions extending inthe third direction Z of the third undulating net 25-3 are separatedfrom the second undulating net 25-2 and form the highest level 24 d ofthe unit three-dimensional net-like structure.

[0181] (g) Step of Fixing the First to Third Undulating Nets

[0182] The first undulating net 25-1, the second undulating net 25-2 andthe third undulating net 25-3 are fixed together at necessary pointsamong points of contact thereof. In FIG. 21, for example, the crossingpoints 24 b of the first undulating net 25-1 and the joining andseparating points 24 b of the portion extending in the third direction Zof the second undulating net 25-2 are fixed together by spot welding,the crossing points 24 c of the second undulating net 25-2 and themiddle point 24 c of the portion extending in the third direction Z ofthe third undulating net 25-3 are fixed together by spot welding, andthe middle point 24 c of the portion extending in the third direction Zof the second undulating net 25-2 and the crossing point 24 c of thethird undulating net 253 are fixed together by spot welding.

[0183] The structure consisting of the first to third undulating netsare laid in plural layers and welded together to form thethree-dimensional net-like structure 30 shown in FIG. 3.

[0184] Further, by applying the method of the embodiment 2, athree-dimensional net-like structure having a unit structure consistingof a polygonal pyramids each having an apex consisting of six lineelements can be formed.

[0185] In the above described embodiments, fixing of the respective lineelements and the undulating nets together is performed by spot welding.The invention is not limited to the spot welding but the line elementsand undulating nets may be fixed together by other methods such assoldering or, in case the line elements are made of plastic, by heatmelting.

What is claimed is:
 1. A method for manufacturing a packing made of athree-dimensional net-like structure which constitutes an internalstructure of a device which performs material transfer, heat exchange ormixing between gases, liquids or gas and liquid, said internal structurebeing divided in a plurality of chambers or channels connected to oneanother and said three-dimensional net-like structure being formed byconversion and dispersion of four line elements, said method comprisingsteps of: (A) disposing first line elements extending in parallel at apredetermined interval in a first direction on a plane and second lineelements extending in parallel at a predetermined interval in a seconddirection which is different from the first direction on the same planein such a manner that the first line elements cross the second lineelements at a desired angle and the first and second line elements arelaid one upon the other; (B) fixing the first line elements to thesecond line elements at crossing points thereof and thereby forming anet; (C) pressing the net to form a plurality of parallel undulatingbulging portions which bulge at alternate ones of the crossing pointscontinuously formed in the first direction and the second direction andthereby forming an undulating net; (D) laying a second layer of theundulating net upon a first layer of the undulating net in such a mannerthat the crossing points continuously formed in the first direction andthe second direction of the first layer of the undulating netalternately come into contact with and separate from the crossing pointscontinuously formed in the first direction and the second direction ofthe second layer of the undulating net and thereafter fixing togetherthe crossing points of the first layer of the undulating net and thesecond layer of the undulating net which are in contact with each other;and (E) laying a third layer of the undulating net upon the second layerof the undulating net in such a manner that the crossing pointscontinuously formed in the first direction and the second direction ofthe second layer of the undulating net alternately come into contactwith and separate from the crossing points continuously formed in thefirst direction and the second direction of the third layer of theundulating net and thereafter fixing together the crossing points of thesecond layer of the undulating net and the third layer of the undulatingnet which are in contact with each other; and thereafter superposing afourth, a fifth . . . and n-th (n being any integer) layer of theundulating nets in the same manner and fixing together the crossingpoints of the respective layers of the undulating nets and theimmediately lower layers of the undulating nets which are in contactwith each other.
 2. A method for manufacturing a packing made of athree-dimensional netlike structure which constitutes an internalstructure of a device which performs material transfer, heat exchange ormixing between gases, liquids or gas and liquid, said internal structurebeing divided in a plurality of chambers or channels connected to oneanother and said three-dimensional net-like structure being formed byconversion and dispersion of three line elements, said methodcomprising: (A) a step of forming a first undulating net comprising thefollowing steps (a), (b) and (c): (a) disposing first line elementsextending in parallel at a predetermined interval in a first directionon a plane and second line elements extending in parallel at apredetermined interval in a second direction which is different from thefirst direction on the same plane in such a manner that the first lineelements cross the second line elements at a desired angle and aresuperposed one upon the other; (b) fixing the first line elements to thesecond line elements at crossing points thereof and thereby forming anet; and (c) pressing the net to form a plurality of parallel undulatingbulging portions and thereby forming a first undulating net in such amanner that one of the crossing points continuously formed in the firstdirection and the second direction constitutes a crossing point of thelowest level in forming of a unit three-dimensional net-like structure,a crossing point adjacent to the crossing point of the lowest levelconstitutes a crossing point of a lower side middle level in forming ofthe unit three-dimensional net-like structure, a crossing point adjacentto the crossing point of the lower side middle level constitutes acrossing point of an upper side middle level in forming of the unitthree-dimensional net-like structure, a crossing point adjacent to thecrossing point of the upper side middle level constitutes a crossingpoint of the lower side middle level in forming of the unitthree-dimensional net-like structure, a crossing point adjacent to thecrossing point of the lower side middle level constitutes a crossingpoint of the lowest level in forming of the unit three-dimensionalnet-like strucuture, and subsequent crossing points constitute crossingpoints of the respective levels in the above cycle in forming of theunit three-dimensional net-like structure; (B) a step of forming asecond undulating net comprising the following steps (a), (b) and (c):(a) disposing first line elements extending in parallel at apredetermined interval in the first direction on a plane, bending at aposition corresponding to one of the crossing points of the lower sidemiddle level of the first undulating net at a predetermined angle andextending in a third direction, bending at a position corresponding tothe next lower side middle point of the first undulating net at thepredetermined angle and extending in the second direction, bending at aposition corresponding to the next lower side middle level of the firstundulating net at the predetermined angle and extending in the thirddirection again, and bending at a position corresponding to the nextlower side middle level of the first undulating net at the predeterminedangle and repeating the cycle of extending in the first direction, thethird direction, the second direction and the third direction, andsecond line elements extending in parallel at a predetermined intervalin the second direction on the plane, bending at a positioncorresponding to one of the crossing points of the lower side middlelevel of the first undulating net at a predetermined angle and extendingin the third direction, bending at a position corresponding to the nextlower side middle point of the first undulating net at the predeterminedangle and extending in the first direction, bending at a positioncorresponding to the next lower side middle level of the firstundulating net at the predetermined angle and extending in the thirddirection again, and bending at a position corresponding to the nextlower side middle level of the first undulating net at the predeterminedangle and repeating the cycle of extending in the second direction, thethird direction, the first direction and the third direction in such amanner that the first line elements and the second line elements crosseach other at the desired angle in their portions extending in the firstor second direction at positions corresponding to the crossing points ofthe upper side middle level of the first undulating net and extendjointly one being laid upon the other in their portions extending in thethird direction; (b) fixing the first line elements to the second lineelements at the respective crossing points thereof and also at joiningpoints and separating points of their portions extending in the thirddirection and thereby forming a net; and (c) pressing the net to form aplurality of parallel undulating bulging portions which bulge at therespective crossing points and also at middle positions of the portionsextending in the third direction and thereby constitute the upper sidemiddle level in forming of the unit three-dimensional net-likestructure, and thereby forming a second undulating net; (C) a step offorming a third undulating net comprising the following steps (a), (b)and (c): (a) disposing first line elements extending in parallel at apredetermined interval in the third direction on a plane, bending at aposition corresponding to one of the crossing points of the lower sidemiddle level of the first undulating net at a predetermined angle andextending in the second direction, bending at a position correspondingto the next lower side middle point of the first undulating net at thepredetermined angle and extending in the third direction again, bendingat a position corresponding to the next lower side middle level of thefirst undulating net at the predetermined angle and extending in thefirst direction, and bending at a position corresponding to the nextlower side middle level of the first undulating net at the predeterminedangle and repeating the cycle of extending in the third direction, thesecond direction, the third direction and the first direction, andsecond line elements extending in parallel at a predetermined intervalin the third direction on the plane, bending at a position correspondingto one of the crossing points of the lower side middle level of thefirst undulating net at a predetermined angle and extending in the firstdirection, bending at a position corresponding to the next lower sidemiddle point of the first undulating net at the predetermined angle andextending in the third direction again, bending at a positioncorresponding to the next lower side middle level of the firstundulating net at the predetermined angle and extending in the seconddirection, and bending at a position corresponding to the next lowerside middle level of the first undulating net at the predetermined angleand repeating the cycle of extending in the third direction, firstdirection, the third direction and the second direction in such a mannerthat the first line elements and the second line elements cross eachother at the desired angle in their portions extending in the first orsecond direction at positions corresponding to middle positions of theportions extending in the third direction of the second undulating netand extend jointly one being laid upon the other in their portionsextending in the third direction; (b) fixing the first line elements tothe second line elements at the crossing points thereof and also atjoining points and separating points of their portions extending in thethird direction and thereby forming a net; and (c) pressing the net toform a plurality of parallel undulating bulging portions which bulge atthe respective joining and separating points of the portions extendingin the third direction and thereby constitute the highest level informing of the unit three-dimensional net-like structure, and therebyforming a third undulating net; (D) a step of laying the secondundulating net upon the first undulating net in such a manner that thecrossing points of the second undulating net come into contact with thecrossing points of the upper middle level of the first undulating net,the joining points and the separating points of the portions extendingin the third direction of the second undulating net come into contactwith the crossing points of the lower middle level of the firstundulating net, and the undulating bulging portions at the middlepositions of the portions extending in the third direction of the secondundulating net are separated from the crossing points of the lowestlevel of the first undulating net and form the upper middle level of theunit three-dimensional net-like structure; (E) a step of laying thethird undulating net upon the second undulating net in such a mannerthat the crossing points of the third undulating net come into contactwith the undulating bulging portions at the middle positions of theportions extending in the third direction of the second undulating net,the portions extending in the third direction of the third undulatingnet come into contact, at their middle positions, with the crossingpoints of the second undulating net, and the undulating bulging portionsat the joining points and the separating points of the portionsextending in the third direction of the third undulating net areseparated from the second undulating net and form the highest level ofthe unit three-dimensional net-like structure; and (F) a step of fixingthe first undulating net, the second undulating net and the thirdundulating net together at necessary points among points of contactthereof.
 3. A method for manufacturing a three-dimensional net-likestructure including a mist eliminator and a multi-layer filtering filmformed by conversion and dispersion of four line elements, said methodcomprising steps of: (A) disposing first line elements extending inparallel at a predetermined interval in a first direction on a plane andsecond line elements extending in parallel at a predetermined intervalin a second direction which is different from the first direction on thesame plane in such a manner that the first line elements cross thesecond line elements at a desired angle and the first and second lineelements are laid one upon the other; (B) fixing the first line elementsto the second line elements at crossing points thereof and therebyforming a net; (C) pressing the net to form a plurality of parallelundulating bulging portions which bulge at alternate ones of thecrossing points continuously formed in the first direction and thesecond direction and thereby forming an undulating net; (D) laying asecond layer of the undulating net upon a first layer of the undulatingnet in such a manner that the crossing points continuously formed in thefirst direction and the second direction of the first layer of theundulating net alternately come into contact with and separate from thecrossing points continuously formed in the first direction and thesecond direction of the second layer of the undulating net andthereafter fixing together the crossing points of the first layer of theundulating net and the second layer of the undulating net which are incontact with each other; and (E) laying a third layer of the undulatingnet upon the second layer of the undulating net in such a manner thatthe crossing points continuously formed in the first direction and thesecond direction of the second layer of the undulating net alternatelycome into contact with and separate from the crossing pointscontinuously formed in the first direction and the second direction ofthe third layer of the undulating net and thereafter fixing together thecrossing points of the second layer of the undulating net and the thirdlayer of the undulating net which are in contact with each other; andthereafter superposing a fourth, a fifth . . . and n-th (n being anyinteger) layer of the undulating nets in the same manner and fixingtogether the crossing points of the respective layers of the undulatingnets and the immediately lower layers of the undulating nets which arein contact with each other.
 4. A method for manufacturing athree-dimensional net-like structure including a mist eliminator and amulti-layer filtering film formed by conversion and dispersion of threeline elements, said method comprising: (A) a step of forming a firstundulating net comprising the following steps (a), (b) and (c): (a)disposing first line elements extending in parallel at a predeterminedinterval in a first direction on a plane and second line elementsextending in parallel at a predetermined interval in a second directionwhich is different from the first direction on the same plane in such amanner that the first line elements cross the second line elements at adesired angle and are superposed one upon the other; (b) fixing thefirst line elements to the second line elements at crossing pointsthereof and thereby forming a net; and (c) pressing the net to form aplurality of parallel undulating bulging portions and thereby forming afirst undulating net in such a manner that one of the crossing pointscontinuously formed in the first direction and the second directionconstitutes a crossing point of the lowest level in forming of a unitthree-dimensional net-like structure, a crossing point adjacent to thecrossing point of the lowest level constitutes a crossing point of alower side middle level in forming of the unit three-dimensionalnet-like structure, a crossing point adjacent to the crossing point ofthe lower side middle level constitutes a crossing point of an upperside middle level in forming of the unit three-dimensional net-likestructure, a crossing point adjacent to the crossing point of the upperside middle level constitutes a crossing point of the lower side middlelevel in forming of the unit three-dimensional net-like structure, acrossing point adjacent to the crossing point of the lower side middlelevel constitutes a crossing point of the lowest level in forming of theunit three-dimensional net-like strucuture, and subsequent crossingpoints constitute crossing points of the respective levels in the abovecycle in forming of the unit three-dimensional net-like structure; (B) astep of forming a second undulating net comprising the following steps(a), (b) and (c): (a) disposing first line elements extending inparallel at a predetermined interval in the first direction on a plane,bending at a position corresponding to one of the crossing points of thelower side middle level of the first undulating net at a predeterminedangle and extending in a third direction, bending at a positioncorresponding to the next lower side middle point of the firstundulating net at the predetermined angle and extending in the seconddirection, bending at a position corresponding to the next lower sidemiddle level of the first undulating net at the predetermined angle andextending in the third direction again, and bending at a positioncorresponding to the next lower side middle level of the firstundulating net at the predetermined angle and repeating the cycle ofextending in the first direction, the third direction, the seconddirection and the third direction, and second line elements extending inparallel at a predetermined interval in the second direction on theplane, bending at a position corresponding to one of the crossing pointsof the lower side middle level of the first undulating net at apredetermined angle and extending in the third direction, bending at aposition corresponding to the next lower side middle point of the firstundulating net at the predetermined angle and extending in the firstdirection, bending at a position corresponding to the next lower sidemiddle level of the first undulating net at the predetermined angle andextending in the third direction again, and bending at a positioncorresponding to the next lower side middle level of the firstundulating net at the predetermined angle and repeating the cycle ofextending in the second direction, the third direction, the firstdirection and the third direction in such a manner that the first lineelements and the second line elements cross each other at the desiredangle in their portions extending in the first or second direction atpositions corresponding to the crossing points of the upper side middlelevel of the first undulating net and extend jointly one being laid uponthe other in their portions extending in the third direction; (b) fixingthe first line elements to the second line elements at the respectivecrossing points thereof and also at joining points and separating pointsof their portions extending in the third direction and thereby forming anet; and (c) pressing the net to form a plurality of parallel undulatingbulging portions which bulge at the respective crossing points and alsoat middle positions of the portions extending in the third direction andthereby constitute the upper side middle level in forming of the unitthree-dimensional net-like structure, and thereby forming a secondundulating net; (C) a step of forming a third undulating net comprisingthe following steps (a), (b) and (c): (a) disposing first line elementsextending in parallel at a predetermined interval in the third directionon a plane, bending at a position corresponding to one of the crossingpoints of the lower side middle level of the first undulating net at apredetermined angle and extending in the second direction, bending at aposition corresponding to the next lower side middle point of the firstundulating net at the predetermined angle and extending in the thirddirection again, bending at a position corresponding to the next lowerside middle level of the first undulating net at the predetermined angleand extending in the first direction, and bending at a positioncorresponding to the next lower side middle level of the firstundulating net at the predetermined angle and repeating the cycle ofextending in the third direction, the second direction, the thirddirection and the first direction, and second line elements extending inparallel at a predetermined interval in the third direction on theplane, bending at a position corresponding to one of the crossing pointsof the lower side middle level of the first undulating net at apredetermined angle and extending in the first direction, bending at aposition corresponding to the next lower side middle point of the firstundulating net at the predetermined angle and extending in the thirddirection again, bending at a position corresponding to the next lowerside middle level of the first undulating net at the predetermined angleand extending in the second direction, and bending at a positioncorresponding to the next lower side middle level of the firstundulating net at the predetermined angle and repeating the cycle ofextending in the third direction, first direction, the third directionand the second direction in such a manner that the first line elementsand the second line elements cross each other at the desired angle intheir portions extending in the first or second direction at positionscorresponding to middle positions of the portions extending in the thirddirection of the second undulating net and extend jointly one being laidupon the other in their portions extending in the third direction; (b)fixing the first line elements to the second line elements at thecrossing points thereof and also at joining points and separating pointsof their portions extending in the third direction and thereby forming anet; and (c) pressing the net to form a plurality of parallel undulatingbulging portions which bulge at the respective joining and separatingpoints of the portions extending in the third direction and therebyconstitute the highest level in forming of the unit three-dimensionalnet-like structure, and thereby forming a third undulating net; (D) astep of laying the second undulating net upon the first undulating netin such a manner that the crossing points of the second undulating netcome into contact with the crossing points of the upper middle level ofthe first undulating net, the joining points and the separating pointsof the portions extending in the third direction of the secondundulating net come into contact with the crossing points of the lowermiddle level of the first undulating net, and the undulating bulgingportions at the middle positions of the portions extending in the thirddirection of the second undulating net are separated from the crossingpoints of the lowest level of the first undulating net and form theupper middle level of the unit three-dimensional net-like structure; (E)a step of laying the third undulating net upon the second undulating netin such a manner that the crossing points of the third undulating netcome into contact with the undulating bulging portions at the middlepositions of the portions extending in the third direction of the secondundulating net, the portions extending in the third direction of thethird undulating net come into contact, at their middle positions, withthe crossing points of the second undulating net, and the undulatingbulging portions at the joining points and the separating points of theportions extending in the third direction of the third undulating netare separated from the second undulating net and form the highest levelof the unit three-dimensional net-like structure; and (F) a step offixing the first undulating net, the second undulating net and the thirdundulating net together at necessary points among points of contactthereof.
 5. A packing made of a three-dimensional net-like structurewhich constitutes an internal structure of a device which performsmaterial transfer, heat exchange or mixing between gases, liquids or gasand liquid, said internal structure being divided in a plurality ofchambers or channels connected to one another and said three-dimensionalnet-like structure being formed by conversion and dispersion of fourline elements wherein a converging portion of the four line elements isformed by mutual contact of undulating nets having parallel undulatingbulging portions at necessary portions.
 6. A packing made of athree-dimensional net-like structure which constitutes an internalstructure of a device which performs material transfer, heat exchange ormixing between gases, liquids or gas and liquid, said internal structurebeing divided in a plurality of chambers or channels connected to oneanother and said three-dimensional net-like structure being formed byconversion and dispersion of three line elements wherein a convergingportion of the three line elements is formed by mutual contact ofundulating nets having parallel undulating bulging portions at necessaryportions.
 7. A three-dimensional net-like structure including a misteliminator and a multi-layer filtering film formed by conversion anddispersion of four line elements wherein a converging portion of thefour line elements is formed by mutual contact of undulating nets havingparallel undulating bulging portions at necessary portions.
 8. Athree-dimensional net-like structure including a mist eliminator and amulti-layer filtering film formed by conversion and dispersion of threeline elements wherein a converging portion of the three line elements isformed by mutual contact of undulating nets having parallel undulatingbulging portions at necessary portions.